Efficacy of lime, biosolids, and mycorrhiza for the phytostabilization of sulfidic copper tailings in Chile: a greenhouse experiment.

Inadequate abandonment of copper mine tailings under semiarid Mediterranean climate type conditions has posed important environmental risks in Chile due to wind and rain erosion. There are cost-effective technologies for tailings stabilization such as phytostabilization. However, this technology has not been used in Chile yet. This study evaluated in a greenhouse assay the efficacy of biosolids, lime, and a commercial mycorrhiza to improve adverse conditions of oxidized Cu mine tailings for adequate establishment and grow of Lolium perenne L. var nui. Chemical characterization of experimental substrates and pore water samples were performed; plant density, biomass production, chlorophyll content, and metal content in shoots was evaluated in rye grass plants after an eight-week growth period. Results showed that neutralization of tailings and superficial application of biosolids increased both aerial biomass production and chlorophyll content of rye grass. Increased Cu solubilization and translocation to shoots occurred after biosolids application (mixed), particularly on unlimed tailings, due to formation of soluble organometallic complexes with dissolved organic carbon (DOC) which can be readily absorbed by plant roots. Positive effects of mycorrhizal inoculation on rye grass growth were restricted to treatments with superficial application of biosolids, probably due to Cu toxicity effects on commercial mycorrhiza used (Glomulus intraradices).

Phytostabilization of copper mine tailings with biosolids: implications for metal uptake and productivity of Lolium perenne.

A greenhouse pot experiment was conducted to evaluate the feasibility of using biosolids and Lolium perenne for the phytostabilization of copper mine tailings and to evaluate the patterns of metal accumulation and translocation in plants. Biosolids were applied either on the surface or mixed with the tailings at rates of 0, 6, and 12% w/w. All pots were seeded with L. perenne and after six months, the plants were harvested and separated into roots and shoots for metal concentrations analyses as well as some physiological characteristics of the plants. In order to correlate the metal content in plant tissues with some chemical properties, the pore-water of the substrates was analyzed for metals, pH and dissolved organic carbon. Results showed that biosolids application increased the dry biomass production of L. perenne and the shoot concentrations of N and chlorophyll. On the other hand, biosolids increased the concentration of Cu and Zn in the pore-water and in plant tissues. Despite this, there were no evident symptoms of phytotoxicity and the concentration of metals was within the normal ranges described for plants and below the maximum tolerable level for animals. In addition, plant tissue analysis showed that the application of biosolids could significantly reduce Mo uptake and shoot accumulation in plants. The metals were taken up by plants in the following order: Cu>Zn>Mo>Cd. The distribution patterns of metals in plants showed that metals were mainly accumulated in the roots and only a small amount of them were transported to the shoots. These results suggest that mixed application of biosolids (6%) and the use of L. perenne could be appropriate for use in programs of phytostabilization of copper mine tailings. However, these results should be tested under field conditions in order to confirm their efficacy under semi-arid Mediterranean climate conditions.

The action of ovarian hormones in cardiovascular disease.

The incidence of cardiovascular disease (CAD) differs between men and women, in part because of differences in risk factors and hormones. This sexual dimorphism means a lower incidence in atherosclerotic diseases in premenopausal women, which subsequently rises in postmenopausal women to eventually equal that of men. These observations point towards estrogen and progesterone playing a lifetime protective role against CAD in women. As exogenous estrogen and estrogen plus progesterone preparations produce significant reductions in low-density lipoprotein (LDL) cholesterol levels and significant increases in high-density lipoprotein (HDL) cholesterol, this should in theory lower the risk of CAD. However, results from oral contraceptive (OC) use and combined estrogen and progesterone hormone replacement therapy (HRT) have suggested that hormone replacement regimes do not provide cardiovascular protection. In fact, depending on the preparation and the presence or absence of genetic risk factors, an increased risk of cardiovascular diseases such as venous thrombosis, myocardial infarction (MI) and stroke have been observed. Interestingly, in the majority of studies the increase in risk was highest in the first year, after which an increase in risk was not observed, and in some studies a lower risk of CAD was evident after four or five years of exogenous hormone administration. While the debate continues about the merits of HRT, and several good reviews exist on the statistics of CAD in relation to exogenous hormones, we have decided to review the literature to piece together the physiological actions of estrogen and progesterone preparations on the individual mechanistic components leading to CAD; namely, the altered endothelium and the haemostatic balance between coagulation and fibrinolysis. We present possible mechanisms for how HRT and OCs protect against MI in the absence of cardiovascular risk factors but increase the incidence of MI in their presence. We also speculate on the roles played by hormones on the short- and long-term risks of cardiovascular disease.

The action of ovarian hormones in cardiovascular disease

The incidence of cardiovascular disease (CAD) differs between men and women, in part because of differences in risk factors and hormones. This sexual dimorphism means a lower incidence in atherosclerotic diseases in premenopausal women, which subsequently rises in postmenopausal women to eventually equal that of men. These observations point towards estrogen and progesterone playing a lifetime protective role against CAD in women. As exogenous estrogen and estrogen plus progesterone preparations produce significant reductions in low-density lipoprotein (LDL) cholesterol levels and significant increases in high-density lipoprotein (HDL) cholesterol, this should in theory lower the risk of CAD. However, results from oral contraceptive (OC) use and combined estrogen and progesterone hormone replacement therapy (HRT) have suggested that hormone replacement regimes do not provide cardiovascular protection. In fact, depending on the preparation and the presence or absence of genetic risk factors, an increased risk of cardiovascular diseases such as venous thrombosis, myocardial infarction (MI) and stroke have been observed. Interestingly, in the majority of studies the increase in risk was highest in the first year, after which an increase in risk was not observed, and in some studies a lower risk of CAD was evident after four or five years of exogenous hormone administration. While the debate continues about the merits of HRT, and several good reviews exist on the statistics of CAD in relation to exogenous hormones, we have decided to review the literature to piece together the physiological actions of estrogen and progesterone preparations on the individual mechanistic components leading to CAD; namely, the altered endothelium and the haemostatic balance between coagulation and fibrinolysis. We present possible mechanisms for how HRT and OCs protect against MI in the absence of cardiovascular risk factors but increase the incidence of MI in their presence. We also speculate on the roles played by hormones on the short- and long-term risks of cardiovascular disease.